Filter device

ABSTRACT

The invention relates to a filter device, comprising a plurality of filter elements ( 21 ), which can be received in a filter housing having a filter inlet for a fluid to be filtered and a filter outlet for the filtered fluid, wherein flow through the filter elements ( 21 ) is possible in both directions for filtration or backwashing. Because the shut-off element ( 41 ) is a fast-closing plate valve ( 43 ), which can be actuated by means of a hydraulic piston ( 53 ) and blocks the fluid connection mentioned above so quickly that a feeding effect is created in the manner of a pressure blow on the backwashed filter element ( 21 ), said feeding effect increasing the cleaning of pollution on the filter element ( 21 ), an improved backwashing cleaning is achieved.

The invention relates to a filter device with a plurality of filter elements according to the configuration of features of the preamble of claim 1.

DE 199 56 859 A1 discloses a filter device which has conically shaped filter elements, in particular in the form of so-called tubular wedge wire screen filter elements. Due to the conical execution, the distance between the individual conical, tubular wedge wire screen filter elements is increased in individual areas, with the result that the outflow space in the filter housing is also enlarged. During backflushing, the conical filter element is distinctly advantageous compared to a cylindrical one. The reason for this is primarily the relatively large exit cross section of the conical filter elements relative to the cylindrical ones for the same filter surface. Since the exit cross section for conical filter elements relative to the entry cross section formed by the filter surface, i.e., the free element area, however, is small, depending on the amount of flow resistance of the split tube, a bottleneck forms in which a large part of the system pressure drops. Therefore, smaller pressure losses occur; this is more favorable in terms of energy in backflushing.

In backflushing, a large part of the volumetric throughput for conical and also for cylindrical filter elements is generally achieved on the lower filter end. The volumetric flows then decrease very quickly. In addition, for conical elements the velocity gradient is smaller, so that including the velocity profile, relative to the filter surface, an additional cleaning effect compared to cylindrical elements arises due to the conicity of the elements. Due to the essentially constant velocity that is achieved in the cleaning of the conical filter elements, this takes place carefully; this prolongs the service life of the pertinent filter elements.

In backflushing, preferably all filter elements are regenerated in succession. During backflushing of individual elements, filtration is continued via the remaining elements so that filtration operation is not interrupted at any time.

In the known filter device, the backflushing process does not take place exclusively in such a way that the overpressure prevailing in the filter device during the backflushing phase allows a partial stream of the filtrate to flow through the filter element to be cleaned in the reverse direction in order to detach and carry away dirt from the element, but in the effort to be able to remove even the most stubborn dirt, to support backflushing, there is a pressure control means which generates a negative pressure on the respective filter element which is to be backflushed. Therefore, not only is the system pressure active in backflushing, but a higher pressure gradient for detaching dirt is available due to the applied negative pressure.

In the known device, the negative pressure means has a hydraulic accumulator in the form of a diaphragm accumulator, the diaphragm, which forms the separating element of the accumulator for intake or pump motion, being connected to the piston rod of a working cylinder. For this actuation, not only is a considerable control effort necessary, but in order to ensure operating reliability, a complex construction of the diaphragm accumulator with a piston rod duct and its sealing is necessary. In spite of an expensive construction, relatively long service lives which ensure operating reliability can hardly be achieved. Moreover, considerable installation space for the accumulator and the drive means is necessary.

DE 10 2005 016 151 A1 discloses a filter device with a housing and a filter inlet for the fluid to be filtered, as well as a filter outlet for the filtered fluid. Within the filter housing, there are several filter elements, the respective filter element having a first through opening which is fluid-connected to the filter inlet and through which during the filtration process dirty fluid flows from the inside to the outside. Furthermore, there is a movable flushing arm with a fluid opening for backflushed dirty fluid that can be fluid-connected to the first passage opening of the filter element, as a result of which a backflushing flow from the outside into the interior of the filter element arises. Because the respective filter element has a second passage opening and there is one valve unit, which in the filtration process closes the second passage opening and opens in the backflushing process, by opening the valve unit in the backflushing process, there arises a second access possibility of the backflushed fluid via the second passage opening that enables an additional backflushing flow within the filter element for obtaining a high degree of cleaning in the backflushing process.

DE 100 24 401 A1 discloses a generic backflushing filter device, in particular for lubricating oil filtration, with filter cartridges which are open on both ends and which are located in the filter housing around a rotary shaft, and whose interior in filter operation can be supplied with the heavy liquid to be filtered which is flowing into the backflush filter and with a cleaning means which is moved by means of the rotary shaft and which, for individual or group cleaning of the filter cartridges in backflushing operation, has at least two so-called flush cocks which are connected to a drain valve via the rotary shaft, the first flush cock being assigned to one end side of the filter cartridge and the other flush cock being assigned to the other end side of the filter cartridge. Because the first flush cock is arranged offset by an angle in the direction of rotation to the second flush cock, and a concomitantly moved first and second sealing member are assigned to the first and second flush cocks for the opposite end side of the filter cartridge, the indicated offset of the flush cocks by an angle in the direction of rotation makes it possible for the filter cartridges to be exposed to the flushing pressure in a delayed mode on the two inflow ends, so that with this backflushing in opposite directions in a delayed mode, high flushing velocities or velocity profiles are achieved over the filter cartridge height; this has a beneficial effect especially in the middle regions between the inflow ends due to the higher flushing velocities which are active there for an improved flushing effect.

With respect to this prior art, the object of the invention is to make available a filter device which, in addition to good filtration performance, can also provide improved backflushing values and which is characterized both by an especially simple construction and also high operating reliability in long-term operation.

According to the invention this object is achieved by a filter device which has the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, the blocking element is a quick-closing plate valve which can be triggered by a hydraulic piston and which quickly blocks the indicated fluid connection such that in the form of a hydraulic shock on the backflushed filter element, a feeding effect arises which increases the removal of dirt on the filter element, improved cleaning is achieved in the backflushing of the respective filter element. Due to the special configuration of the blocking element, in the fluid flow which enters the filter element before the backflushing process, an abrupt flow interruption occurs so that the flow velocity, which prevails in the blocking process as a flow-dynamic effect, causes a strong feeding effect. For the flow through the filter element which is reversed relative to filtration, therefore, not only is the system pressure available on the clean side of the pertinent filter element, but the backflow of filtrate is intensified by the feeding effect available as a result of the indicated dynamic effect which arises by the sudden blocking of the flow which is flowing in from the contaminated side. With the solution according to the invention, a type of hydraulic shock function arises whose action is improved to the extent conical filter elements are used. The latter then cause a feeding effect uniformly over the entire element and not only in defined middle areas, as indicated in the prior art.

The plate valve used, as a blocking element of the pressure control means, enables an especially simple construction which is favorable in production. Furthermore, the plate valve requires little installation space and, in this respect, can be easily integrated into the filter housing. Moreover, operating reliability is ensured over virtually unlimited operating times.

Preferably, the filter elements have an inner filter cavity which defines a longitudinal axis extending between the end-side input opening that is connected to the filter inlet during filtration, and an end-side discharge opening opposite thereto, via which, in the course of backflushing, the contaminated fluid can be discharged, the input opening of the filter element to be cleaned for backflushing being blockable by means of the blocking element, and, preferably, there being filter elements located with a vertical longitudinal axis in the filter housing with a shape that is tapered conically to the top; as already mentioned above, among other factors, this promotes efficiency of backflushing, viewed over the entire element.

In advantageous exemplary embodiments, the discharge opening of the filter element to be cleaned can be connected to a backflushing line which can be alternately cleared or blocked by a valve means. This yields the additional option of controlling the flow in the outflow region of the dirty fluid. In particular, when the arrangement here is such that the backflushing line has a length that is greater or considerably greater than the length of the filter elements measured in the direction of the longitudinal axis, then, by controlling the flow velocity of a comparatively long fluid column, a dynamic effect which develops an especially strong feeding effect and thus especially effective cleaning is achieved.

In preferred exemplary embodiments, the backflushing means has a movable backflushing arm which can be connected by a drive means to the discharge opening of the filter element to be cleaned, and the blocking element in the course of motion of the backflushing arm by the drive means can be aligned to the input opening of the filter element which is connected to the backflushing arm in order to clear or block fluid entry into its filter cavity.

The invention is detailed below, using one exemplary embodiment shown in the drawings.

FIG. 1 shows schematically and not to scale one embodiment of the invention in a longitudinal section;

FIG. 2 shows an extract which has been enlarged relative to FIG. 1 according to the region designated as II in FIG. 1;

FIG. 3 shows a schematically greatly simplified partial extract of the device drawn markedly shortened in the vertical direction, a filter element prepared for backflushing and a fluid flow passing through it being shown schematically, and

FIG. 4 shows a representation similar to FIG. 3 for illustration of the fluid flow which prevails in the actual backflushing process.

The filter device shown in the figures has a cylindrical housing 1 with an upper sealing cover 3, a lower housing termination 5, and an interposed intermediate bottom 7, all of which can be fixed on the filter housing 1 by way of flange connections 9. In the housing 1, the intermediate bottom 7 separates a space 11 for the unfiltered material, into which fluid to be filtered can flow via the filter inlet 13, from the clean side 15 of the filter device, from where filtered fluid can be discharged via the filter outlet 17.

Between the intermediate bottom 7 and an element receiver 19 located on the lower housing termination 5, filter elements 21, which run conically upward, are inserted, and, in place of the conical filter elements 21, there can also be at least partially cylindrical filter elements (not shown). The indicated conical filter elements 21, which can consist of so-called tubular wedge wire screen filter elements, are arranged at distances from one another along a cylindrical arc within the filter housing 1. In one embodiment which is not detailed, there can also be filter elements 21 in groups subdivided repeatedly along cylindrical arcs.

The filter elements 21 shown in the drawings with their inlet cross sections, i.e., with their input opening 23, discharge into recesses 24 of the intermediate bottom 7 which are made correspondingly cylindrical, therefore are fluid-connected to the space 11 which contains the unfiltered material so that for the filtration process it enters the inner filter cavity 25 of the filter elements 21 and in filtration flows through the filter elements 21 to the outside toward the clean side. In the backflushing process, conversely, flow takes place from the outside to the inside through the respective filter element which is to be cleaned, from the clean side 15. By way of a pivotally mounted backflushing arm 27, which forms the start of a backflushing line 29 that leads out of the filter housing 1, the dirty fluid, which contains the detached dirt, in the backflushing process flows via a bottom-side discharge opening 31 out of the filter element 21 which is being cleaned.

The backflushing arm 27 for its pivoting motion can be driven by means of a geared motor 33 by way of a drive shaft means, which is located concentrically in the filter housing 1 and which has an upper shaft journal 35 that is attached to the driven side of the geared motor 33, a hollow intermediate shaft 37, and a lower shaft journal 39 which is connected to the backflushing arm 37.

The geared motor 33 is used not only to pivot the backflushing arm 27, but also forms the pivot drive for a blocking element 41 by means of which for a backflushing process the fluid connection between the unfiltered material in the space 11 and the filter cavity 25 of the filter element 21 to be cleaned can be stopped by its input opening 23 being closed. The relevant details of the blocking element 41 containing the plate valve 43 are illustrated in FIGS. 2 to 4.

As is apparent from these figures, the plate valve 43 is located on a carrier 45 which is connected to the shaft journal 35 so that the geared motor 33 pivots the plate valve 43 together with the backflushing arm 27. In the figures, by means of the geared motor 33, the backflushing arm 27 and the plate valve 43 are set into the pivot position in which the filter element 21, located on the left side in the figures, is chosen for a backflushing process. The plate valve 43 has a valve plate 47 which interacts with the valve seat 49 on the carrier 45. For the closing motion taking place along the longitudinal axis 51 for lining up the valve plate 47 and thus for blocking the input opening 23 of the pertinent filter element 21, the valve plate 47 can be moved by means of a hydraulic piston 53 which is guided in a hydraulic cylinder 55 which is connected to the carrier 45.

To illustrate the mode of operation, reference is made especially to FIGS. 3 and 4. FIG. 3 shows by flow arrows 57 (not all numbered in the figures) how the fluid flow runs in the filter element 21 selected for a backflushing process, to whose input opening 23 the plate valve 43 is aligned and whose discharge opening 31 is connected to the backflushing arm 27. This flow state shown in FIG. 3 prevails when a valve means 59, which is shown only in FIG. 1, clears the backflushing line 29 and the plate valve 43 is not yet closed. If, at this point, for the backflushing process, the plate valve 43 is closed in this flow state, i.e., the afterflow of unfiltered material out of the space 11 into the filter element 21 is blocked, the flow is reversed on the filter element 21. As a result of the flow velocity of the unfiltered material flowing through the filter element 21 from the space 11 (state from FIG. 3), blocking of the plate valve 43 leads to a negative hydraulic shock, as a result of which a feeding effect arises, so that for the backflow indicated with the flow arrows 61 in FIG. 4 into the filter element 21 from the standpoint of the clean side 15, not only the system pressure, but in addition a feeding effect, are available by the blocking of the unfiltered liquid column. Even the most stubborn dirt is detached from the filter medium by the nozzle action which arises in this way at the passage sites of the filter medium. An especially strong feeding effect occurs when the backflushing line 29 has a greater length, i.e., the blocking process takes place at flow velocities which correspond to a relatively long fluid column. 

1. A filter device with a plurality of filter elements (21) which can be received in a filter housing (1) with a filter inlet (13) for a fluid to be filtered and a filter outlet (17) for the filtered fluid, and flow can take place through the filter elements (21) for filtration or backflushing in both directions, at the same time some filter elements (21) undertaking filtration and at least one other filter element (21) can be backflushed for cleaning of its active filter surface by a backflushing means which contains a pressure control means for support of backflushing, the pressure control means having a blocking element (41) by means of which the fluid connection between the filter inlet (13) and the filter element (21) to be cleaned can be blocked or cleared, and during filtration the blocking element (41) clearing the fluid connection and blocking it with the start of backflushing or during it, characterized in that the blocking element (41) is a quick-closing plate valve (43) which can be triggered by a hydraulic piston (53) and which quickly blocks the indicated fluid connection such that in the manner of a hydraulic shock on the backflushed filter element (21), a feeding effect arises which increases the removal of dirt on the filter element (21).
 2. The filter device according to claim 1, characterized in that the filter elements (21) have an inner filter cavity (25) which defines a longitudinal axis (51) that extends between the end-side input opening (23) that is connected to the filter inlet (13) during filtration, and an end-side discharge opening (31) opposite thereof, and via which, in the course of backflushing, the dirty fluid can be discharged, and that the input opening (23) of the filter element (21) to be cleaned for backflushing can be blocked by means of the blocking element (41).
 3. The filter device according to claim 1, characterized in that there are filter elements (21) located with a vertical longitudinal axis (51) in the filter housing (1), with a shape that is tapered conically to the top.
 4. The filter device according to claim 2, characterized in that the discharge opening (31) of the filter element (21) to be cleaned can be connected to a backflushing line (29) which can be alternately cleared or blocked by a valve means (59).
 5. The filter device according to claim 4, characterized in that the backflushing line (29) has a length that is greater than the length of the filter elements (21) measured in the direction of the longitudinal axis (51).
 6. The filter device according to claim 2, characterized in that the backflushing means has a movable backflushing arm (27) that can be connected by a drive means (33) to the discharge opening (31) of the filter element (21) to be cleaned, and that the blocking element (41) in the course of motion of the backflushing arm (27) by the drive means (33) can be aligned to the input opening (23) of the filter element (21), which is connected to the backflushing arm (27), in order to clear or block fluid entry into its filter cavity (25). 